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Wed, 09 Dec 2020 11:33:12 +0000 Received: from outbound-smtp13.blacknight.com ([46.22.139.230]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kmxiW-00005M-Vx for linux-arm-kernel@lists.infradead.org; Wed, 09 Dec 2020 11:33:10 +0000 Received: from mail.blacknight.com (pemlinmail02.blacknight.ie [81.17.254.11]) by outbound-smtp13.blacknight.com (Postfix) with ESMTPS id 938031C3E96 for ; Wed, 9 Dec 2020 11:33:02 +0000 (GMT) Received: (qmail 24101 invoked from network); 9 Dec 2020 11:33:02 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.22.4]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 9 Dec 2020 11:33:02 -0000 Date: Wed, 9 Dec 2020 11:33:00 +0000 From: Mel Gorman To: "Li, Aubrey" Subject: Re: [PATCH 2/4] sched/fair: Move avg_scan_cost calculations under SIS_PROP Message-ID: <20201209113300.GN3371@techsingularity.net> References: <20201208153501.1467-1-mgorman@techsingularity.net> <20201208153501.1467-3-mgorman@techsingularity.net> <3255625e-fa92-dc09-9fab-5621122f4af0@linux.intel.com> <20201209090507.GM3371@techsingularity.net> <14963d1e-02ea-c298-d6b4-2db637913ee3@linux.intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <14963d1e-02ea-c298-d6b4-2db637913ee3@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201209_063309_139010_9A3D5CC9 X-CRM114-Status: GOOD ( 13.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Barry Song , Juri Lelli , Vincent Guittot , Peter Ziljstra , LKML , Ingo Molnar , Valentin Schneider , Linux-ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Dec 09, 2020 at 07:07:11PM +0800, Li, Aubrey wrote: > On 2020/12/9 17:05, Mel Gorman wrote: > > On Wed, Dec 09, 2020 at 01:28:11PM +0800, Li, Aubrey wrote: > >>>> nr = div_u64(span_avg, avg_cost); > >>>> else > >>>> nr = 4; > >>>> - } > >>>> - > >>>> - time = cpu_clock(this); > >>>> > >>>> - cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr); > >>>> + time = cpu_clock(this); > >>>> + } > >>>> > >>>> for_each_cpu_wrap(cpu, cpus, target) { > >>>> if (!--nr) > >> > >> nr is the key of this throttling mechanism, need to be placed under sched_feat(SIS_PROP) as well. > >> > > > > It isn't necessary as nr in initialised to INT_MAX if !SIS_PROP. > >If !SIS_PROP, nr need to -1 then tested in the loop, instead of testing directly. > But with SIS_PROP, need adding a test in the loop. > Since SIS_PROP is default true, I think it's okay to keep the current way. > It's because it's default true and the cost is negligible that I'm leaving it alone. The branch cost and nr accounting cost is negligible and it avoids peppering select_idle_cpu() with too many SIS_PROP checks. -- Mel Gorman SUSE Labs _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel